This research is aimed at the development of a clinical device to measure corneal oxygen consumption noninvasively. The device will operate by measuring the rate of decrease of the oxygen tension in a membrane reservoir applied briefly to the cornea. Mathematical analysis of the resulting data will give oxygen consumption in the component layers of the cornea. The aims of Phase I are to establish the technical merit and feasibility of the operating principles of the monitor. Phase II will lead to the development of a prototype oxygen consumption monitor for commercial application. The ultimate goal is to have such a device generally available for clinical procedures such as corneal measurements to evaluate the most appropriate contact lens material, especially for extended wear lenses. Phase I aims are grouped in three main categories: 1. Development of mathematical models to be used in the theoretical treatment of the measured rate of oxygen tension (PO2) decrease recorded following application of the sensor to the cornea. 2. Modification of an existing polarographic oxygen electrode to a preprototype oxygen uptake sensor. The main feature will be the isolation of the cornea from the electrode by an intervening oxygen reservoir membrane. 3. Testing and evaluation of the preprototype in vitro, as well as using rabbit corneas, to determine its engineering and physiological feasibility.